An Expandable hanger and packer

ABSTRACT

An apparatus and method of creating a seal between two coaxial tubulars so as to create a hanger and a packer. A first tubular is disposed coaxially within a portion of a second, larger tubular. A portion of the first tubular is expanded into frictional contact with the second tubular, thereby creating a liner and a hanger. In one embodiment, a pattern of grooves is formed in the surface of a portion of the first tubular body. The grooves in one aspect define a continuous pattern about the circumference of the tubular body which intersect to form a plurality of substantially identical shapes, such as diamonds. The grooves serve to improve the tensile strength of the tubular body. At the same time, the grooves allow for expansion of the tubular body by use of less radial force. The grooves further provide a gripping means, providing additional frictional support for hanging the expanded tubular onto the inner surface of a surrounding second tubular. The apparatus and method optionally provides a pliable material fabricated within the grooves on the outer surface of the tubular body. In addition, carbide inserts are preferably interdisposed within the pattern of grooves, providing additional gripping means when the smaller diameter tubular body is expanded into the second tubular.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to wellbore completion. Moreparticularly, the invention relates to an apparatus and method forcreating an attachment and a seal between two tubulars in a wellbore.

[0003] 2. Description of the Related Art

[0004] In the drilling of oil and gas wells, a wellbore is formed usinga drill bit that is urged downwardly at a lower end of a drill string.After drilling a predetermined depth, the drill string and bit areremoved, and the wellbore is lined with a string of steel pipe calledcasing. The casing provides support to the wellbore and facilitates theisolation of certain areas of the wellbore adjacent hydrocarbon bearingformations. The casing typically extends down the wellbore from thesurface of the well to a designated depth. An annular area is thusdefined between the outside of the casing and the earth formation. Thisannular area is filled with cement to permanently set the casing in thewellbore and to facilitate the isolation of production zones and fluidsat different depths within the wellbore.

[0005] It is common to employ more than one string of casing in awellbore. In this respect, a first string of casing is set in thewellbore when the well is drilled to a first designated depth. The wellis then drilled to a second designated depth, and a second string ofcasing, or liner, is run into the well to a depth whereby the upperportion of the second liner is overlapping the lower portion of thefirst string of casing. The second liner string is then fixed or hung inthe wellbore, usually by some mechanical slip mechanism well-known inthe art, and cemented. This process is typically repeated withadditional casing strings until the well has been drilled to totaldepth.

[0006] After the initial string of casing is set, the wellbore isdrilled to a new depth. An additional string of casing, or liner, isthen run into the well to a depth whereby the upper portion of theliner, is overlapping the lower portion of the surface casing. The linerstring is then fixed or hung in the wellbore, usually by some mechanicalslip mechanism well known in the art, commonly referred to as a hanger.

[0007] Downhole tools with sealing elements are placed within thewellbore to isolate areas of the wellbore fluid or to manage productionfluid flow from the well. These tools, such as plugs or packers, forexample, are usually constructed of cast iron, aluminum or other alloyedmetals and include slip and sealing means. The slip means fixes the toolin the wellbore and typically includes slip members and cores towedgingly attach the tool to the casing well. In addition to slip means,conventional packers include a synthetic sealing element located betweenupper and lower metallic retaining rings.

[0008] The sealing element is set when the rings move towards each otherand compress the element there between, causing it to expand outwardsinto an annular area to be sealed and against an adjacent tubular orwellbore. Packers are typically used to seal an annular area formedbetween two coaxially disposed tubulars within a wellbore. For example,packers may seal an annulus formed between production tubing disposedwithin wellbore casing. Alternatively, packers may seal an annulusbetween the outside of the tubular and an unlined borehole. Routine usesof packers include the protection of casing from pressure, both well andstimulation pressures, as well as the protection of the wellbore casingfrom corrosive fluids. Other common uses include the isolation offormations or leaks within a wellbore casing or multiple productionzones, thereby preventing the migration of fluid between zones. Packersmay also be used to hold fluids or treating fluids within the casingannulus in the case of formation treatment, for example.

[0009] One problem associated with conventional sealing and slip systemsof conventional down hole tools relates to the relative movement of theparts necessary in order to set the tools in a wellbore. Because theslip and sealing means require parts of the tool to be moved in opposingdirections, a run-in tool or other mechanical device must necessarilyrun into the wellbore with the tool to create the movement.Additionally, the slip means takes up valuable annular space in thewellbore. Also, the body of a packer necessarily requires wellbore spaceand reduces the bore diameter available for production tubing, etc.

[0010] A recent trend in well completion has been the advent ofexpandable tubular technology. It has been discovered that both slottedand solid tubulars can be expanded in situ so as to enlarge the innerdiameter. This, in turn, enlarges the path through which both fluid anddownhole tools may travel. Also, expansion technology enables a smallertubular to be run into a larger tubular, and then expanded so that aportion of the smaller tubular is in contact with the larger tubulartherearound. Tubulars are expanded by the use of a cone-shaped mandrelor by an expander tool with expandable, fluid actuated members disposedon a body and run into the wellbore on a tubular string. Duringexpansion of a tubular, the tubular walls are expanded past theirelastic limit. Examples of expandable tubulars include slotted screen,joints, packers, and liners. The use of expandable tubulars as hangersand packers allows for the use of larger diameter production tubing,because the conventional slip mechanism and sealing mechanism areeliminated.

[0011] While expanding tubulars in a wellbore offers obvious advantages,there are problems associated with using the technology to create ahanger or packer through the expansion of one tubular into another. Byplastically deforming the tubular, the cross-sectional thickness of thetubular is necessarily reduced. Simply increasing the initialcross-sectional thickness of the tubular to compensate for the reducedtensile strength after expansion results in an increase in the amount offorce needed to expand the tubular.

[0012] More importantly, when compared to a conventional hanger, anexpanded tubular with no gripping structure on the outer surface has areduced capacity to support the weight of a liner. This is due to areduced coefficient of friction of the outer surface of an expandabletubular in comparison to the slip mechanism having teeth or othergripping surfaces formed thereon.

[0013] A need therefore exists for an expandable tubular connection withincreased strength. There is a further need for an expandable tubularconnection providing an improved gripping surface between an expandedtubular and an inner wall of a surrounding tubular.

[0014] A further need exists for an expandable tubular with an increasedcapacity to support the weight of a liner.

SUMMARY OF THE INVENTION

[0015] The present invention generally relates to an apparatus andmethod for engaging a first tubular and a second tubular in a wellbore.The present invention provides a tubular body formed on a portion of afirst tubular. The tubular body is expanded so that the outer surface ofthe tubular body is in frictional contact with the inner surface of asurrounding second tubular. In one embodiment, the tubular body ismodified by machining grooves into the surface, thereby reducing theamount of radial force required to expand the tubular body on the firsttubular into the surrounding tubular.

[0016] The tubular body optionally includes hardened inserts, such ascarbide buttons, for gripping the surrounding tubular upon contact. Thegripping mechanism increases the capacity of the expanded tubular tosupport its weight and to serve as a hanger. In another aspect, theouter surface of the expandable tubular body optionally includes apliable material such as an elastomer within grooves formed on the outersurface, and for increasing the sealing capability of the expandabletubular to an outer tubular.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] So that the manner in which the above recited features,advantages and objects of the present invention are attained and can beunderstood in detail, a more particular description of the invention,briefly summarized above, may be had by reference to the embodimentsthereof which are illustrated in the appended drawings.

[0018] It is to be noted, however, that the appended drawings illustrateonly typical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

[0019]FIG. 1 is a perspective view of a tubular having grooves formed inthe outer surface, and having inserts of a hardened material alsodisposed around the outer surface.

[0020]FIG. 2 is a section view of the tubular of FIG. 1.

[0021]FIG. 3 is an exploded view of an exemplary expander tool.

[0022]FIG. 4 is a partial section view of a tubular of the presentinvention within a wellbore, and showing an expander tool attached to aworking string also disposed within the tubular.

[0023]FIG. 5 is a partial section view of the tubular of FIG. 4partially expanded by the expander tool.

[0024]FIG. 6 is a partial section view of an expanded tubular in thewellbore with the expander tool and working string removed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025]FIG. 1 is a perspective view of the apparatus of the presentinvention. The apparatus 200 defines a tubular body formed on a portionof a larger tubular. The tubular body 200 shown in FIG. 1 includes aseries of grooves 210 machined into the outer surface. However, it iswithin the scope of the present invention to machine some or all of thegrooves 210 into the inner surface of the expandable tubular 200. Therelief grooves 210 serve to reduce the thickness of the tubular 200,thereby reducing the amount of material that must be plasticallydeformed in order to expand the tubular 200. This reduction in materialalso results in a reduction in the amount of force needed to expand thetubular 200.

[0026] As shown in FIG. 1, the grooves 210 are machined in a definedpattern. Employment of a pattern of grooves 210 serves to increase thetensile properties of the tubular 200 beyond those of a tubular withstraight grooves simply cut around the circumference of the tubular.This improvement in tensile properties is due to the fact that thevariation in cross-sectional thickness will help to prevent thepropagation of any cracks formed in the tubular. The pattern of groovesdepicted in FIG. 1 is a continuous pattern of grooves 210 about thecircumference of the body 200, with the grooves 210 intersecting to forma plurality of substantially identical shapes. In the preferredembodiment, the shapes are diamonds. However, the scope of thisinvention is amenable to other shapes, including but not limited topolygonal shapes, and interlocking circles, loops or ovals (not shown).

[0027]FIG. 1 also depicts inserts 220 interdisposed within the patternof grooves 210. The inserts 220 provide a gripping means between theouter surface of the tubular 200 and the inner surface of a largerdiameter tubular (not shown) within which the tubular 200 is coaxiallydisposed. The inserts 220 are made of a suitably hardened material, andare attached to the outer surface of the tubular 200 through a suitablemeans such as soldering, epoxying or other adhesive method, or viathreaded connection. In the preferred embodiment, carbide inserts 220are press-fitted into preformed apertures in the outer surface oftubular body 200. After expansion, the inserts 220 are engaged with theinner surface of a larger diameter tubular (not shown), therebyincreasing the ability of the expanded tubular 200 to support the weightof the tubular below the expanded portion.

[0028] In the embodiment shown in FIG. 1, carbide inserts 220 areutilized as the gripping means. However, other materials may be used forfabrication of the inserts 220 so long as the inserts 220 aresufficiently hard to be able to grip the inner surface of an outertubular during expansion of the tubular body 200. Examples offabrication materials for the inserts 220 include ceramic materials(such as carbide) and hardened metal alloy materials. The carbideinserts 220 define raised members fabricated into the tubular body 200.However, other embodiments of gripping means may alternatively beemployed. Such means include but are not limited to buttons having teeth(not shown), or other raised or serrated members on the outer surface ofthe expandable tubular 200. Alternatively, the gripping means may definea plurality of hardened tooth patterns added to the outer surface of thetubular body 200 between the grooves 210 themselves.

[0029] The embodiment of FIG. 1 also depicts a pliable material 230disposed within the grooves 210. The pliable material 230 increases theability of the tubular 200 to seal against an inner surface of a largerdiameter tubular upon expansion. In the preferred embodiment, thepliable member 230 is fabricated from an elastomeric material. However,other materials are suitable which enhance the fluid seal sought to beobtained between the expanded portion of tubular 200 and an outertubular, such as surface casing (not shown). The pliable material 230 isdisposed within the grooves 210 by a thermal process, or some other wellknown means. A thin layer of the pliable material 230 may alsoencapsulate the inserts 220 and facilitate the attachment of the inserts220 to the tubular 200.

[0030]FIG. 2 is a section view of a portion of the tubular 200 ofFIG. 1. In this view, the inserts 220 are shown attached to the tubular200 in the areas between the grooves 210. In this respect, the inserts220 are interdispersed within the pattern of grooves 210. FIG. 2 alsoclearly shows the reduction in cross-sectional thickness of the tubular200 created by the grooves 210 before expansion.

[0031] The inserts 220 in FIG. 2 have a somewhat conical shapeprojecting from the outer surface of the tubular 200 to assist inengagement of the inserts 200 into an outer tubular (shown in FIG. 4).For clarity, the inserts are exaggerated in the distance they extendfrom the surface of the tubular. In one embodiment, the inserts extendonly about 0.03 inches outward prior to expansion. In anotherembodiment, the raised members 220 are initially recessed, eitherpartially or competely, with respect to the tubular 200, and then extendat least partially outward into contact with the casing after expansion.Such an embodiment is feasible for the reason that the wall thickness ofthe tubular 200 becomes thinned during the expansion process, therebyexposing an otherwise recessed raised member.

[0032] The tubular body 200 of the present invention is expanded by anexpander tool 100 acting outwardly against the inside surface of thetubular 200. FIG. 3 is an exploded view of an exemplary expander tool100 for expanding the tubular 200. The expander tool 100 has a body 102which is hollow and generally tubular with connectors 104 and 106 forconnection to other components (not shown) of a downhole assembly. Theconnectors 104 and 106 are of a reduced diameter compared to the outsidediameter of the longitudinally central body part of the tool 100. Thecentral body part 102 of the expander tool 100 shown in FIG. 3 has threerecesses 114, each holding a respective roller 116. Each of the recesses114 has parallel sides and extends radially from a radially perforatedtubular core (not shown) of the tool 100. Each of the mutually identicalrollers 116 is somewhat cylindrical and barreled. Each of the rollers116 is mounted by means of an axle 118 at each end of the respectiveroller 116 and the axles are mounted in slidable pistons 120. Therollers 116 are arranged for rotation about a respective rotational axisthat is parallel to the longitudinal axis of the tool 100 and radiallyoffset therefrom at 120-degree mutual circumferential separations aroundthe central body 102. The axles 118 are formed as integral end membersof the rollers 116, with the pistons 120 being radially slidable, onepiston 120 being slidably sealed within each radially extended recess114. The inner end of each piston 120 is exposed to the pressure offluid within the hollow core of the tool 100 by way of the radialperforations in the tubular core. In this manner, pressurized fluidprovided from the surface of the well, via a working string 310, canactuate the pistons 120 and cause them to extend outward whereby therollers 116 contact the inner wall of a tubular 200 to be expanded.

[0033]FIG. 4 is a partial section view of a tubular 200 of the presentinvention in a wellbore 300. The tubular 200 is disposed coaxiallywithin the casing 400. An expander tool 100 attached to a working string310 is visible within the tubular 200. Preferably, the tubular 200 isrun into the wellbore 300 with the expander tool 100 disposed therein.The working string 310 extends below the expander tool 100 to facilitatecementing of the tubular 200 in the wellbore 300 prior to expansion ofthe tubular 200 into the casing 400. A remote connection (not shown)between the working, or run-in, string 310 and the tubular 200temporarily connects the tubular 200 to the run-in string 310 andsupports the weight of the tubular 200. In one embodiment of the presentinvention, the temporary connection is a collett (not shown), and thetubular 200 is a string of casing.

[0034]FIG. 4 depicts the expander tool 100 with the rollers 116retracted, so that the expander tool 100 may be easily moved within thetubular 200 and placed in the desired location for expansion of thetubular 200. Hydraulic fluid (not shown) is pumped from the surface tothe expander tool 100 through the working string 310. When the expandertool 100 has been located at the desired depth, hydraulic pressure isused to actuate the pistons (not shown) and to extend the rollers 116 sothat they may contact the inner surface of the tubular 200, therebyexpanding the tubular 200.

[0035]FIG. 4 also shows carbide inserts 220 attached to the outersurface of the tubular 200. Because the tubular 200 has not yet beenexpanded, the carbide inserts 220 are not biting the casing 400 so as toform a grip between the tubular 200 and casing 400. FIG. 4 also shows apliable material 230 disposed within the grooves 210.

[0036]FIG. 5 is a partial section view of the tubular 200 partiallyexpanded by the expander tool 100. At a given pressure, the pistons (notshown) in the expander tool 100 are actuated and the rollers 116 areextended until they contact the inside surface of the tubular 200. Therollers 116 of the expander tool 100 are further extended until therollers 116 plastically deform the tubular 200 into a state of permanentexpansion. The working string 310 and the expander tool 100 are rotatedduring the expansion process, and the tubular 200 is expanded until thetubular's outer surface contacts the inner surface of the casing 400. Asthe tubular 200 contacts the casing 400, the inserts 220 begin to engagethe inner surface of the casing 400. In addition, the pliable material230 fills the void created between the grooves 210 and the casing 400,thereby improving the sealing characteristics of the interface betweenthe expanded tubular 200 and the casing 400. The working string 310 andexpander tool 100 are then translated within the tubular 200 until thedesired length of the tubular 200 has been expanded.

[0037]FIG. 6 is a partial section view of an expanded tubular 200 in awellbore 300, with the expander tool 100 and working string 310 removed.FIG. 6 depicts the completed expansion process, after which the expandedportion of the tubular 200 defines both a packer and a hanger. As apacker, the expanded portion of the tubular 200 seals the annular areabetween the casing 400 and the tubular 200. As a hanger, the expandedportion of the tubular 200 supports the weight of the tubular 200.

[0038]FIG. 6 demonstrates the inserts 220 engaging the inner surface ofthe casing 400. The engagement of the inserts 220 into the casing 400enable the expanded portion of the tubular 200 to support an increasedweight in comparison to an expanded tubular without inserts. The inserts220 axially and rotationally fix the outer surface of the expandedtubular 200 to the inner surface of the casing 400. Further, the pliablematerial 230 fills the grooves 210 machined into the tubular 200 isdisposed in the interface between the expanded tubular 200 and thecasing 400. In addition, the pliable material may also encapsulate theinserts 220 and provide a means of attaching the inserts 220 to thetubular 200.

[0039] While the foregoing is directed to embodiments of the presentinvention, other and further embodiments of the invention may bedirected without departing from the basic scope thereof, and the scopethereof is determined by the claims that follow.

1. An apparatus for engaging a first tubular and a second tubular in awellbore, the apparatus comprising: a tubular body formed on the firsttubular, having an inner surface and an outer surface, said tubular bodybeing expandable radially outward into contact with an inner wall of thesecond tubular by the application of an outwardly directed forcesupplied to the inner surface of said tubular body; and gripping meansformed on the outer surface of said tubular body for increasing frictionbetween the first and second tubulars upon expansion of said tubularbody.
 2. The apparatus of claim 1, wherein said gripping means definesat least one raised member.
 3. The apparatus of claim 2, wherein said atleast one raised member defines a plurality of inserts.
 4. The apparatusof claim 3, wherein said plurality of inserts are fabricated from ahardened metal alloy.
 5. The apparatus of claim 3, wherein saidplurality of inserts are fabricated from a ceramic material.
 6. Theapparatus of claim 2, wherein said at least one raised member defines aplurality of buttons having teeth.
 7. The apparatus of claim 1, whereinsaid gripping means includes relief grooves formed in the outer surfaceof said tubular body.
 8. The apparatus of claim 7, wherein said groovesare formed in a pattern.
 9. The apparatus of claim 8, wherein thepattern of said grooves is a continuous pattern about the circumferenceof the body, the grooves intersecting to form a plurality ofsubstantially identical shapes.
 10. The apparatus of claim 9, whereinsaid grooves are substantially filled with a pliable material.
 11. Theapparatus of claim 10, wherein said substantially identical shapes arediamonds.
 12. An apparatus for engaging a first tubular and a secondtubular in a wellbore, the apparatus comprising: a tubular body formedon the first tubular, having an inner surface and an outer surface, saidtubular body being expandable radially outward into contact with aninner wall of the second tubular by the application of an outwardlydirected force supplied to the inner surface of said tubular body; andrelief grooves formed in a surface of said tubular body.
 13. Theapparatus of claim 12, wherein said relief grooves are formed in theouter surface of said tubular body.
 14. The apparatus of claim 13,wherein said grooves are formed in a pattern.
 15. The apparatus of claim14, wherein the pattern of said grooves is a continuous pattern aboutthe circumference of the body, said grooves intersecting to form aplurality of substantially identical shapes.
 16. The apparatus of claim15, wherein said grooves are substantially filled with a pliablematerial.
 17. The apparatus of claim 16, wherein said substantiallyidentical shapes are diamonds.
 18. The apparatus of claim 14 furthercomprising gripping means formed on the outer surface of said tubularbody for further increasing friction between the first and secondtubulars upon expansion of said tubular body.
 19. The apparatus of claim18, wherein said gripping means defines raised members extending outwardfrom the outer surface of said body.
 20. The apparatus of claim 19,wherein said raised members define inserts interdisposed in the patternof said grooves.
 21. The apparatus of claim 20 wherein said inserts arefilled into preformed apertures in the outer surface of said tubularbody.
 22. The apparatus of claim 21, wherein said inserts are fabricatedfrom a hardened metal alloy.
 23. The apparatus of claim 21, wherein saidplurality of inserts are fabricated from a ceramic material.
 24. Theapparatus of claim 20, wherein said raised members defines a pluralityof buttons having teeth.
 25. The apparatus of claim 19 wherein the firstand the second tubular are each a string of casing.
 26. A method ofcompleting a wellbore comprising the steps of: providing a firsttubular, said first tubular having a pattern of relief grooves on anouter surface of a portion thereof; positioning a second tubular withina wellbore positioning said first tubular coaxially within a portion ofsaid second tubular, said second tubular having an inner diameter whichis larger than the outer diameter of said first tubular; positioning anexpander tool within said first tubular at a depth proximate the patternof said grooves; activating said expander tool so as to apply a force tothe inner surface of said first tubular, thereby expanding said firsttubular such that the outer surface of said first tubular is infrictional contact with the inner surface of said second tubular; 27.The method of completing a wellbore of claim 26, wherein said groovesare disposed in a continuous pattern about the circumference of saidfirst tubular body, said grooves intersecting to form a plurality ofsubstantially identical shapes.
 28. The method of completing a wellboreof claim 27, wherein said grooves are substantially filled with apliable material; and wherein said step of activating of said expandertool is accomplished by applying hydraulic force to a plurality ofroller members disposed radially about the expander tool.
 29. The methodof completing a wellbore of claim 28, wherein said substantiallyidentical shapes are diamonds.
 30. The method of completing a wellboreof claim 29 further comprising the step of positioning gripping means onthe outer surface of said tubular body interdispersed between saidgrooves for further increasing friction between the first and secondtubulars upon expansion of said first tubular.
 31. The method of claim30, wherein said gripping means defines a plurality of raised membersextending outward from the outer surface of said first tubular.
 32. Themethod of claim 31, wherein said plurality of raised members defineinserts filled into preformed apertures in the outer surface of saidfirst tubular.
 33. The method of claim 32, wherein said inserts arefabricated from a hardened alloy material.
 34. The method of claim 32,wherein said inserts are fabricated from a ceramic material.
 35. Themethod of claim 31, wherein said plurality of raised members areinitially recessed at least partially within the wall of said tubularbody, but then protrude from the outer surface of said tubular body uponexpansion of said tubular body.
 36. The method of claim 32, wherein saidplurality of raised members defines a plurality of buttons having teeth.37. The method of claim 30, wherein said gripping means defines aplurality of hardened tooth patterns added to the outer surface of thetubular body between said grooves.
 38. The method of claim 27 whereinthe first and the second tubular are each a string of casing.